diff --git a/README.md b/README.md
index cd06f4a..72e3e73 100644
--- a/README.md
+++ b/README.md
@@ -399,5 +399,6 @@ this package will read `.json` file, and generate `.dart` file, asign the `type
 | asign list of type and import (can also be recursive) | {`...`:`"$[]value"`} | `{"addreses":"$[]address"}` | `List<Address> addreses;` | `import 'address.dart'` |
 | import other library(input value can be array) | {`"@import"`:`...`} | `{"@import":"package:otherlibrary/otherlibrary.dart"}` | | `import 'package:otherlibrary/otherlibrary.dart'` |
 | Datetime type | {`...`:`"@datetime"`} | `{"createdAt": "@datetime:2020-02-15T15:47:51.742Z"}` | `DateTime createdAt;` | |
-| Enum type | {`...`:`"@enum:(folowed by enum separated by ',')"`} | `{"@import":"@enum:admin,app_user,normal"}` | `enum UserTypeEnum { Admin, AppUser, Normal }` |
-| Enum type with values  {`...`:`"@enum:(folowed by enum separated by ',')"`} | `{"@import":"@enum:admin(0),app_user(1),normal(2)"}`                            | `enum UserTypeEnum { Admin, AppUser, Normal }`| |
+| Enum type | {`...`:`"@enum:(folowed by enum separated by ',')"`} | `{"@import":"@enum:admin,app_user,normal"}` | `enum UserTypeEnum { Admin, AppUser, Normal }` ||
+| Enum type with values  {`...`:`"@enum:(folowed by enum separated by ',')"`} | `{"@import":"@enum:admin(0),app_user(1),normal(2)"}`                            | `enum UserTypeEnum { Admin, AppUser, Normal }`| ||
+| Custom class key (support private key, such as _InfoModel. By the way, not only in array, but also in normal object.) | {"$key": "CustomClassName"} | {"info":{"$key": "InfoModel", "name?":"Nick"}} | class InfoModel{final String? name; ...} ||
diff --git a/lib/core/command.dart b/lib/core/command.dart
index 0855b46..2dd4da2 100644
--- a/lib/core/command.dart
+++ b/lib/core/command.dart
@@ -39,8 +39,13 @@ DartDeclaration defaultCommandCallback(DartDeclaration self, dynamic testSubject
   }
 
   if (value is Map) {
-    self.type = key.toTitleCase();
-    self.nestedClasses.add(JsonModel.fromMap(key, value as Map<String, dynamic>));
+    String customKey = key;
+    if (value['\$key'] != null && value['\$key'] != '') {
+      customKey = value['\$key'] as String;
+    }
+    value.remove('\$key');
+    self.type = customKey.toTitleCase();
+    self.nestedClasses.add(JsonModel.fromMap(customKey, value as Map<String, dynamic>));
     return self;
   }
 
@@ -49,16 +54,16 @@ DartDeclaration defaultCommandCallback(DartDeclaration self, dynamic testSubject
     if (firstListValue is List) {
       final nestedFirst = firstListValue.first;
       if (nestedFirst is Map) {
-        final key = nestedFirst['\$key'];
+        final key = nestedFirst['\$key'] as String;
         nestedFirst.remove('\$key');
-        self.type = 'List<List<$key>>';
-        self.nestedClasses.add(JsonModel.fromMap(key as String, nestedFirst as Map<String, dynamic>));
+        self.type = 'List<List<${key.toTitleCase()}>>';
+        self.nestedClasses.add(JsonModel.fromMap(key, nestedFirst as Map<String, dynamic>));
       }
     } else if (firstListValue is Map) {
-      final key = firstListValue['\$key'];
+      final key = firstListValue['\$key'] as String;
       firstListValue.remove('\$key');
-      self.type = 'List<$key>';
-      self.nestedClasses.add(JsonModel.fromMap(key as String, firstListValue as Map<String, dynamic>));
+      self.type = 'List<${key.toTitleCase()}>';
+      self.nestedClasses.add(JsonModel.fromMap(key, firstListValue as Map<String, dynamic>));
     } else {
       final listValueType = firstListValue.runtimeType.toString();
       self.type = 'List<$listValueType>';
@@ -158,7 +163,7 @@ final List<Command> keyComands = [
 ];
 
 final List<Command> valueCommands = [
-   Command(
+  Command(
     prefix: '#',
     callback: (DartDeclaration self, dynamic testSubject, {required String key, dynamic value}) {
       final subject = testSubject as String;
diff --git a/lib/utils/extensions.dart b/lib/utils/extensions.dart
index 85345d0..ef3e332 100644
--- a/lib/utils/extensions.dart
+++ b/lib/utils/extensions.dart
@@ -5,6 +5,9 @@ import 'package:json_to_model/core/model_template.dart';
 extension StringExtension on String {
   String toTitleCase() {
     final firstWord = toCamelCase();
+    if (firstWord.startsWith(RegExp('_'))) {
+      return '_${firstWord.substring(1, 2).toUpperCase()}${firstWord.substring(2)}';
+    }
     return '${firstWord.substring(0, 1).toUpperCase()}${firstWord.substring(1)}';
   }
 
@@ -32,12 +35,14 @@ extension StringExtension on String {
 
   List<String> getWords() {
     List<String> value;
-
+    bool isPrivate = false;
+    if (startsWith(RegExp('_'))) {
+      isPrivate = true;
+    }
     value = trim().split(RegExp(r'[_\W]'));
     value = value.where((element) => element.isNotEmpty).toList();
     value = value.expand((e) => e.split(RegExp('(?=[A-Z])'))).where((element) => element.isNotEmpty).toList();
-
-    return value;
+    return isPrivate ? ['_', ...value] : value;
   }
 
   bool isTitleCase() {